Impact tool



Dec. 25, 1962 E. G. SPYRIDAKIS 3,070,201

IMPACT' TOOL Filed March 2. 1960 w m HIS AT ORNEY Unite States Patent Ofiice 3,670,291 Patented Dec. 25, 1962 3,079,291 IMPACT TQQL Emanuel G. pyridakis, Athens, Pa., assignor to Ingersoii- Rand iCornpany, New York, N.Y., a corporation of New Jersey Filed Mar. 2, 1966, Ser. No. 12,329 4 Claims. ill. 192-30.5)

This invention relates to intermittently engageable clutches, and particularly those of the type adapted to strike impacts that are especially useful in machines such as impact wrenches and the like.

As heretofore constructed, wrenches of this sort utilize the driving end of such a clutch as a hammering element which intermittently engages the driven member of the clutch with a striking blow. Means is provided to disengage the clutch upon striking whereupon the driving or hammer member picks up speed and through the medium of a driving mechanism the clutch re-engages to strike a succeeding blow. This action is repeated until the operator turns off the actuating power.

The blows are struck at a part of a revolution or at most at each full turn of the hammer element. The force of the blows depends to a great extent upon the speed of the hammer member at the moment of striking. As generally constructed, the speed at striking is much less than the free rotational speed of the hammer member. If the hammer speed can be increased, the weight of the hammer can be reduced greatly, which becomes evident by realization that the energy in the hammer member is directly proportional to the weight of the hammer (which is a function of its moment of inertia) but proportional to the square of its velocity. The great advantages of this increase in speed are obvious; either increased power or great reduction in size and particularly the weight of the tool.

It is accordingly an object of this invention to provide a clutch for use in an impact wrench and the like that will increase the power of the tool for a given driving load capacity and tool weight or alternatively to reduce the size and weight of such a tool.

Other objects and advantages of the invention will become in part obvious and be in part pointed out hereinafter in the following description of a preferred embodiment of the invention, in which FIGURE 1 is a fragmentary view of an impact wrench showing in longitudinal section the improved clutch,

FIG. 2 is a cross sectional view taken along the line 22 looking in the direction of the arrows,

FIG. 3 is a sectional view taken along the line 33 looking in the direction of the arrows,

FIG. 4 is a diagrammatic development of the jaws of the driving and driven members indicating the relative positions of the jaws and indicates also how they are actuated to strike, and

FIG. 5 is a diagrammatic representation of the actuating cams for timing the jaw cooperation whereby the jaw engagement is accomplished.

Referring to the drawings and more particularly to FIG. 1, there is illustrated part of a tool known generally as an impact wrench including those elements which are essential to this invention. The tool is housed in a casing in two parts, the rear part containing the motor, indicated at 12, and having a drive shaft 14 extending into the nose portion 16 of the casing.

The clutch proper includes a driving member 18 having jaws 20 intermittently adapted to engage jaws 22 of the driven member 24. The motor 12 and driving member 18 have a splined connection, as shown at 26, and additionally the driving member 18 is rotationally mounted in the casing part 10, there being an anti-friction bearing 28 provided for this purpose.

In order to reduce the weight of reciprocating parts, the jaws of the driving member, which will be hereinafter referred to as the hammer jaws 2t), are formed separately from the main body 18 of the driving member. As shown more clearly in FIG. 2, the jaws 20, three in number, project forwardly from the sort of crab element 39. The element 3th is slidably mounted in forwardly projecting arms 32 of the main body 13 of the driven member.

The driven member 24 is essentially a cylindrical stem rotatably mounted in a bushing 34 in the front casing portion 16 and extends forwardly from the casing 16 to receive a working implement, such as a wrench socket 36. As shown in FIG. 4, there are three jaws 22 on the driven element 24 to correspond with the three driving member jaws 2t In an impact tool, the driven member 24 is usually called the anvil, and the jaws 22, the anvil jaws. The jaws 24), as has been said above, are ordinarily called the hammer jaws and the part 18, the hammer.

From what has been said above, it will be readily understood that the principal function of the jaws 20 and 22 is to give and receive, respectively, an impact; and this, as is understood, will be in a rotational direction for forcibly rotating the working implement 36. To this end, means is provided normally biased to disengage the driving and driven members 18 and 24, respectively, and this includes a coil spring 38 compressively interposed between the anvil 24 and the hammer ,jaws 2d; and it is intended that this spring shall disengage the jaws 2t) and 22 after each impact, preferably. Means is provided to periodically re-engage the jaw members 2% and 22 and this is done by timing elements associated with said members. These timing elements may assume various forms but their action is preferably essentially that of camming.

For purposes of simplicity there is here: shown a earn 4%) carried by the non-reciprocable portion of the driving element 18 which is adapted to engage cam 42 formed integrally with the hammer jaws 20 at the rear face of the crab-like portion 30. The bump on the cam 40 is on the edge of a cylindrical piece 44 rotatable in a recess 46, in this instance, eccentrically of the hammer is. In this instance, the cam 42 rotates with the hammer jaws 20', and, as will be seen, cam 46 will have to be timed at some rotative speed relatively thereto or the hammer jaws 2% would never be pushed forward to engage the anvil jaws 22.

The timing of the cam 40, therefore, in this instance is accomplished by the relative motion of the driving element or hammer 1% with respect to the anvil 24. T 0 this end, there is provided a shaft 48 extending into the anvil 24 and keyed to the anvil by a dowel 51 extending into the head 52 of shaft 48. The head 52 provides a convenient abutment for the biasing spring 38 as well.

Shaft 48 extends upwardly, as the tool is positioned in FIG. 1, through the center of the crab 30 and at its upper end is journaled in a bushing 54 which is mounted concentrically in the hammer 18. For engagement and timing of the cam 40, the shaft 48 is geared to the cylindrical sleeve 44. Spur gear teeth 56 are cut lengthwise of the shaft 48 adjacent the bushing 54, and for engagement therewith the cylindrical member 44 is cut with internal teeth 58 as shown most clearly in FIG. 3.

The gear ratio indicated in FIG. 3 is two to one. As a consequence, there will be two rotations of the hammer 18 with respect to the anvil 24 to cause coincidence of the came '40 and 42 once as indicated in PEG. 5. It is, of course, understood that when these cams meet, they do not merely slide over one another since the velocity of one with respect to the other is quite high. As a resuit, the cam 42 tends to be thrown forward, and by the time the cam 40' has traveled beyond to a position as indicated at 41, the hammer cam will be depressed to a position as shown at 43.

These motions, of course, are relative with respect to the two cams, and the hammer jaws are actually being thrown forward toward the anvil jaw 22. The hammer jaw motion is indicated more clearly in FIG. 4. The actual rise of the earns 49 and 42 is relatively slight and were it not for inertia effect, the hammer jaws 21 would probably never strike the anvil jaws 22. The strength of the spring 38 is such that the hammer jaws 21 do not recover before striking the anvil jaws 22. Due to their inertia, the hammer jaws 2% will be fiung forward to a position such as shown at 21 whereupon, of course, the hammer stops or, at least, tends to stop depending upon the resistance of the implement 36. After the hammer jaws Zii have stopped, the spring 38 restores those jaws 2% to their position for re-engagement of the cams 4d and 42 upon further rotation.

It will be seen from the above that the degree of rotation between driven and driving members 24 and 18, to cause engagement respectively, depends upon the gear ratio of the shaft 48 and member 44. If, for instance, it be desired that hammering take place upon rotation of the hammer 18 at one and one-third revolution, then that gear ratio should be three to four, at one and two-thirds revolution, three to five, and so on. The advantage of this timing is that after stopping, the hammer 13 has a longer time to gather speed and thus strike a harder blow.

it will be noted, of course, that the lighter the hammer 18 the quicker it will gather speed all of which contributes to augment the desired efifect or heavy blows.

It is understood that many changes may be made within the spirit of the invention, and it is intended that such should be included within the scope of the appended claims.

I claim:

1. An intermittently engagable clutch comprising a rotatable driving member, a rotatable driven member, a jaw on each of said members mutually engagable to couple said members, biasing means to disengage said members, a first cam element associated with said driving member for conjoined rotation therewith, a second cam element mounted for rotation to periodically engage the first cam element and thereby cause one of said jaws to engage said other jaw, a gear associated with said second cam element for conjoined rotation with the latter, said second cam element and said gear being mounted with their axes of rotation eccentrically disposed with respect to the axis of rotation of said first cam element and the driving member, a second gear connected to. the driven member for conjoined rotation with the latter and disposed in meshing relationship with the first mentioned gear so that upon relative rotation of said driving and driven members said first mentioned gear and. said second cam element are rotated relative to the rotation of said driving member and thereby efi'ect engagement of said first and second cam elements once in every rotation of the driving member in excess of one complete revolution of the driving member to cause one of said jaws to engage said other jaw.

2. An intermittently engagable clutch comprising a rotatable driving member, a rotatable driven member having a spindle, a jaw on each of said members mutually engagable to couple said members together, spring means to disengage said members, a cam element associated with said driving member for conjoined rotation therewith, a

second cam element mounted on said driving member for rotation relative to the latter, said first and second cam elements being mounted to periodically engage each other and thereby cause one of said jaws to engage said other jaw, a first gear associated with said second cam element for conjoined rotation with the latter, said second cam element and said first gear being mounted with their axes of rotation eccentric-ally disposed with respect to the axes of rotation of said first cam element and said spindle, a second gear on said spindle disposed in meshing relationship with the first gear so that upon relative rotation of said driving and driven members said first gear and said second cam element are rotated relative to the rotation of said driving member to efiect thereby engagement of said first and second cam elements once in every rotation of the driving member in excess of one complete revolution of the driving member and one of said jaws to engage said other jaw.

3. In an impact tool, an intermittently engageable clutch comprising a rotatable hammer, a rotatable anvil having a spindle and an impact receiving jaw, an impact delivering jaw carried by said hammer for conjoined rotation with the latter and axially movable relative to said hammer, spring means disposed to bias said impact receiving jaw and said impact delivering jaw out of engagement with each other, a first cam element associated with said impact delivering jaw for conjoined rotation and axial movement with the latter, a second cam element supported by the hammer for relative rotation with respect to the hammer, a first gear associated with said second cam element for conjoined rotation with the latter, said first and second cam elements being mounted to periodically engage each other and dimensioned to effect axial movement of said impact delivering jaw into engaging relationship with the impact receiving jaw, said first gear and said second cam element being mounted with their axes of rotation eccentrically disposed with respect to the axes of rotation of said first cam element and said spindle, a second gear connected to the spindle and in meshing relationship with said first gear so that upon relative rotation of said hammer and anvil said first gear and said second cam element are rotated relative to the rotation of the hammer to effect thereby engagement of said first and second cam elements once in every rotation of the hammer in exces of one complete revolution of the hammer and axial movement of said impact delivering jaw into engagement with the impact receiving jaw.

4. An impact clutch for an impact tool comprising a rotatable hammer, a rotatable anvil, a spindle connected to said anvil for conjoined rotation with the latter, at least one impact receiving jaw on said anvil, at least one impact delivering jaw carried by said hammer for conjoined rotation with the latter and axially movable relative to said hammer to engage said impact receiving jaw, a spring disposed between the anvil and said impact delivering jaw to bias said impact receiving and delivering jaws out of engagement, a first cam element associated with said impact delivering jaw for conjoined rotation and axial movement with the latter, a second cam element supported by the hammer for relative rotation with respect to the hammer a first gear integral with said second cam element, said first and second cam elements being mounted to periodically engage each other and dimensioned to effect axial movement of said impact delivering jaw into engaging relationship with the impact receiving ja-w, said first gear and second cam element being mounted with their axes of rotation eccentrically disposed with respect to the axes of rotation of said first cam element and said spindle, a second gear integral with said spindle disposed to mesh with said first gear so that upon relative rotation of said hammer and anvil said first gear and said second cam element are rotated relative to the rotation of the hammer to efiect thereby engagement of said first and sec- 0nd cam elements once in every rotation of the hammer in excess of one complete revolution of the hammer and axial movement of said impact delivering jaw into engagement with the impact receiving jaw.

References Cited in the file of this patent UNITED STATES PATENTS 1,467,773 Bennett Sept. 11, 1923 2,339,530 Van Sittert et al. Jan. 18, 1944 2,339,531 Van Sittert et al. Jan. 18, 1944 2,825,436 Amtsberg Mar. 4, 1958 2,932,992 Larsh Apr. 19, 1960 

